Advances in Remote Sensing-based Disaster Monitoring and Assessment

Remote sensing data and techniques have been widely used for disaster monitoring and assessment. In particular, recent advances in sensor technologies and artificial intelligence-based modeling are very promising for disaster monitoring and readying responses aimed at reducing the damage caused by disasters. This book contains eleven scientific papers that have studied novel approaches applied to a range of natural disasters such as forest fire, urban land subsidence, flood, and tropical cyclones

Оценка и автоматизированное картографирование современной лесистости овражно-балочных систем Белгородской области на основе спутниковых данных

Анализ спектрально-отражательных свойств покрытых лесом участков овражно-балочных систем Белгородской области, оценка возможностей спутниковых данных Sentinel-2 для их автоматизированного картографировани

Assesment of biomass and carbon dynamics in pine forests of the Spanish central range: A remote sensing approach

Forests play a dynamic role in the terrestrial carbon (C) budget, by means of the biomass stock and C fluxes involved in photosynthesis and respiration. Remote sensing in combination with data analysis constitute a practical means for evaluation of forest implications in the carbon cycle, providing spatially explicit estimations of the amount, quality, and spatio-temporal dynamics of biomass and C stocks. Medium and high spatial resolution optical data from satellite-borne sensors were employed, supported by field measures, to investigate the carbon role of Mediterranean pines in the Central Range of Spain during a 25 year period (1984-2009). The location, extent, and distribution of pine forests were characterized, and spatial changes occurred in three sub-periods were evaluated. Capitalizing on temporal series of spectral data from Landsat sensors, novel techniques for processing and data analysis were developed to identify successional processes at the landscape level, and to characterize carbon stocking condition locally, enabling simultaneous characterization of trends and patterns of change. High spatial resolution data captured by the commercial satellite QuickBird-2 were employed to model structural attributes at the stand level, and to explore forest structural diversity

Ecology of Savanna Ecosystems in Indonesia

Tropical savannas in South East Asia are important yet understudied ecosystems. In fact, the description of savanna is limited in the Indonesian Archipelago, a region which, based on climate alone, would be expected to have mostly forest. In this thesis, I compared and contrasted the vegetation characteristics of four savannas in the wetter part of the Indonesian archipelago (Java – Bali – Lombok) to understand how fire and grazing influence their dynamics, and searched for evidence of savanna origins, maintenance, invasion by exotic/woody species and possible ecosystem transitions. Vegetation surveys, remote sensing techniques and statistical models were used to spatially and temporally analyse the savanna community composition and the environmental variables and disturbances that influence their structure. there are distinct elevation gradients (along with related climatic factors such as temperature and precipitation), as well as fire regime gradients, linked to tropical savanna community composition across Java, Bali and Lombok Islands. These compositions are characterized by different sets of species, and where invasive alien species are becoming significant components of the ecosystems. Lack of prescribed fire and a range of invasive species threaten to convert savanna at Bali Barat and Alas Purwo into secondary forests or shrubland, whereas the presence of forest pioneer/edge species within the savanna at Rinjani suggests successional change from grassland to forest may occur in the absence of future fires (although the role of soil, topography and microclimate in maintaining grass dominance needs also to be further explored). Compared to the others studied, the savanna in Baluran National Park has characteristics of being relatively old and persistent rather than one being created and maintained via recent human conversion of forests. Overall in Indonesia, there is much less savanna compared to forests, hence it is expected that a greater percentage of savanna is burned. Using remote sensing analysis, I confirmed that approximately 2% of savanna/open vegetation had burned over a 14 year period, whereas only 0.8% of forest has burned across Indonesia. The extent and frequency of burning is mostly associated with annual Southern Oscillation Index (SOI). Most burning occurred in years when the SOI sustained negative SOI values, which generally means drier conditions across South East Asia. I also developed species distribution models for the main invasive alien species of the savanna ecosystems studied, Acacia nilotica, to establish its invasion potential, both locally in Baluran National Park and regionally in other parts of Indonesia. Acacia nilotica was different from the other invasive species studied, in that it is promoted by herbivory, and possibly also by fire. It appears that spatially, A. nilotica is rapidly advancing into the savanna of Baluran National Parks where it was observed that over fourteen years the savanna size has decreased (-1,361 ha), whilst the A. nilotica stand has increased in area (+ 1,886 ha). It was demonstrated that fire and grazing play an important role in this invasion. Results also show that global climate change is likely to increase the potential distribution of A. nilotica in Indonesia and the area at risk of invasion. By year 2045, A. nilotica has potential to spread across much of the eastern parts of Indonesia. As fire and grazing are common to savannas of eastern Indonesia, they are likely to facilitate its invasion into these areas. In summary, I have shown that savanna plant community in Indonesia is formed and maintained by interactions between climatic factors, fire regime and grazing. Invasive species were also present in the studied savannas such as Chromolaena odorata, and Lantana camara. These invasive species together with forest pioneer/edge specialist species (Ficus septica, Laportea stimulans, Melastoma polyanthum, Nauclea orientalis, Rubus rosifolius), may also be increasing in absence of fire and also may be leading to change of state from savanna to dense woody vegetation. Absence of fire seems to be changing structure and floristic of savanna vegetation which has implications for savanna species including rare fauna such as Jalak Bali/Bali Starling (Leucopsar rotschildi) and Javan Banteng/Wild Java cattle (Bos javanicus subsp. javanicus). Results from this thesis showed that Bali Starling range in Bali Island has shrunk to remaining small patches of fire-induced open shrub and savanna woodland found below an elevation of 150–175 m in the north-east part of peninsular Prapat Agung of Bali Barat National Park. The description of the savanna dynamics presented here provides further evidence of the complexity of the savanna ecosystem and its susceptibility to change as a result of changing fire regimes and invasion by invasive species. A greater understanding of the possible ecosystem processes driving the dynamics of the savannas will assist in the formulation of successful savanna management strategies at local and regional scales

Exploiting growing stock volume maps for large scale forest resource assessment: Cross-comparisons of ASAR- and PALSAR-based GSV estimates with forest inventory in Central Siberia

Growing stock volume is an important biophysical parameter describing the state and dynamics of the Boreal zone. Validation of growing stock volume (GSV) maps based on satellite remote sensing is challenging due to the lack of consistent ground reference data. The monitoring and assessment of the remote Russian forest resources of Siberia can only be done by integrating remote sensing techniques and interdisciplinary collaboration. In this paper, we assess the information content of GSV estimates in Central Siberian forests obtained at 25m from ALOS-PALSAR and 1km from ENVISAT-ASAR backscatter data. The estimates have been cross-compared with respect to forest inventory data showing 34% relative RMSE for the ASAR-based GSV retrievals and 39.4% for the PALSAR-based estimates of GSV. Fragmentation analyses using a MODIS-based land cover dataset revealed an increase of retrieval error with increasing fragmentation of the landscape. Cross-comparisons of multiple SAR-based GSV estimates helped to detect inconsistencies in the forest inventory data and can support an update of outdated forest inventory stands

Remote sensing environmental change in southern African savannahs : a case study of Namibia

Savannah biomes cover a fifth of Earth’s surface, harbour many of the world’s most iconic species and most of its livestock and rangeland, while sustaining the livelihoods of an important proportion of its human population. They provide essential ecosystem services and functions, ranging from forest, grazing and water resources, to global climate regulation and carbon sequestration. However, savannahs are highly sensitive to human activities and climate change. Across sub-Saharan Africa, climatic shifts, destructive wars and increasing anthropogenic disturbances in the form of agricultural intensification and urbanization, have resulted in widespread land degradation and loss of ecosystem services. Yet, these threatened ecosystems are some of the least studied or protected, and hence should be given high conservation priority. Importantly, the scale of land degradation has not been fully explored, thereby comprising an important knowledge gap in our understanding of ecosystem services and processes, and effectively impeding conservation and management of these biodiversity hotspots. The primary drivers of land degradation include deforestation, triggered by the increasing need for urban and arable land, and concurrently, shrub encroachment, a process in which the herbaceous layer, a defining characteristic of savannahs, is replaced with hardy shrubs. These processes have significant repercussions on ecosystem service provision, both locally and globally, although the extents, drivers and impacts of either remain poorly quantified and understood. Additionally, regional aridification anticipated under climate change, will lead to important shifts in vegetation composition, amplified warming and reduced carbon sequestration. Together with a growing human population, these processes are expected to compound the risk of land degradation, thus further impacting key ecosystem services. Namibia is undergoing significant environmental and socio-economic changes. The most pervasive change processes affecting its savannahs are deforestation, degradation and shrub encroachment. Yet, the extent and drivers of such change processes are not comprehensively quantified, nor are the implications for rural livelihoods, sustainable land management, the carbon cycle, climate and conservation fully explored. This is partly due to the complexities of mapping vegetation changes with satellite data in savannahs. They are naturally spatially and temporally variable owing to erratic rainfall, divergent plant functional type phenologies and extensive anthropogenic impacts such as fire and grazing. Accordingly, this thesis aims to (i) quantify distinct vegetation change processes across Namibia, and (ii) develop methodologies to overcome limitations inherent in savannah mapping. Multi-sensor satellite data spanning a range of spatial, temporal and spectral resolutions are integrated with field datasets to achieve these aims, which are addressed in four journal articles. Chapters 1 and 2 are introductory. Chapter 3 exploits the Landsat archive to track changes in land cover classes over five decades throughout the Namibian Kalahari woodlands. The approach addresses issues implicit in change detection of savannahs by capturing the distinct phenological phases of woody vegetation and integrating multi-sensor, multi-source data. Vegetation extent was found to have decreased due to urbanization and small-scale arable farming. An assessment of the limitations leads to Chapter 4, which elaborates on the previous chapter by quantifying aboveground biomass changes associated with deforestation and shrub encroachment. The approach centres on fusing multiple satellite datasets, each acting as a proxy for distinct vegetation properties, with calibration/validation data consisting of concurrent field and LiDAR measurements. Biomass losses predominate, demonstrating the contribution of land management to ecosystem carbon changes. To identify whether biomass is declining across the country, Chapter 5 focuses on regional, moderate spatial resolution time-series analyses. Phenological metrics extracted from MODIS data are used to model observed fractional woody vegetation cover, a proxy for biomass. Trends in modelled fractional woody cover are then evaluated in relation to the predominant land-uses and precipitation. Negative trends slightly outweighed positive trends, with decreases arising largely in protected, urban and communal areas. Since precipitation is a fundamental control on vegetation, Chapter 6 investigates its relation to NDVI, by assessing to what extent observed trends in vegetation cover are driven by rainfall. NDVI is modelled as a function of precipitation, with residuals assumed to describe the fraction of NDVI not explained by rainfall. Mean annual rainfall and rainfall amplitude show a positive trend, although extensive “greening” is unrelated to rainfall. NDVI amplitude, used as a proxy for vegetation density, indicates a widespread shift to a denser condition. In Chapter 7, trend analysis is applied to a Landsat time-series to overcome spatial and temporal limitations characteristic of the previous approaches. Results, together with those of the previous chapters, are synthesized and a synopsis of the main findings is presented. Vegetation loss is predominantly caused by demand for urban and arable land. Greening trends are attributed to shrub encroachment and to a lesser extent conservation laws, agroforestry and rangeland management, with precipitation presenting little influence. Despite prevalent greening, degradation processes associated with shrub encroachment, including soil erosion, are likely to be widespread. Deforestation occurs locally while shrub encroachment occurs regionally. This thesis successfully integrates multi-source data to map, measure and monitor distinct change processes across scales